1. Field of the Invention
This invention relates generally to pressure regulators for pressurized cylinders, and more particularly to a pressure regulator having a pressure-operated warning indicator that signals cylinder depletion.
2. Background Information
Pressurized cylinders or tanks are used in a wide variety of applications, such as gas welding equipment in which a supply of inert gas is delivered to a work station. Typically, the quantity of gas remaining in the cylinder is determined by a pressure gauge. Higher cylinder pressures readings indicate a greater quantity of gas within the cylinder.
Pressure regulators are commonly used with pressurized cylinders to reduce the varying and relatively high fluid pressure within the tank to a substantially constant and relatively lower delivery pressure. Typically, regulators employ a spring biased differential piston to control a throttling seat to regulate pressure. In general, regulators are either of the direct-acting type wherein the regulator seat closes against the inlet pressure, or the indirect-acting type wherein the regulator seat closes with the inlet pressure. In one prior art pressure regulator of the indirect-acting type illustrated in U.S. Pat. No. 4,622,857, pressure gauges are connected to the inlet and outlet sides of the regulator for determining tank pressure and delivery pressure respectively.
The use of conventional pressure gauges and regulators with gas cylinders has presented certain problems. For example, gas welding operators need a signal indicating the near depletion of the gas cylinder. Many pressure gauges cannot be read from a distance or from any direction. A welder is often required to stop work to move closer to face the gauge directly. Trial and error is required to learn how much welding time is available for a given gauge reading. Thus, there has been a need for an inexpensive warning indicator on pressurized cylinders indicating the near depletion of gas which can be easily seen by the operator.